4.3.2.4. Adaptation and Vulnerability

The hydrological situations expected to be of most concern in the region are
the water-limited drought-prone areas, the exposure of the built environment
to possible increases in flooding, the supply of potable water to remote indigenous
populations in inland Australia and on low-lying islands, and the progressive
loss of snowfields.

Integrated catchment management provides an adaptation framework for the long-term
management of catchment water and surface properties and the short-term tradeoffs
between competing demands for water. Already, major systems such as Australia's
Murray-Darling River system are subject to intensive management, but generally
this does not include consideration of possible decadal-scale changes or even
of the predictable El Niņo-related seasonal-to-annual variations. Water pricing
and water efficiency initiatives may be used as an effective adaptation strategy
(Fenwick, 1995; McClintock, 1997). The risk of landslides and soil erosion can
be reduced through informed land management, particularly by avoiding vegetation
clearance in vulnerable areas and by rehabilitating exposed areas that have
been cleared.

Urban planning and management will be needed to deal with increased flooding
risk-for example through provision of retention basins and zoning. Any slow
change in mean rainfall or rainfall intensity, if well-enough known in advance,
could be accommodated within the lead time of about 10 years needed for planning
and constructing major facilities. Dams and flood-protection works can be redesigned
and rebuilt and vulnerable buildings relocated, albeit at considerable cost.
However, any slow increase in interannual rainfall variability may result in
early stresses for supply systems designed to cope with existing rainfall variability;
at such times, the adaptation options would be very limited, as was shown during
the public water supply crisis in Auckland in 1994. Measures needed to improve
the water supply situation of indigenous peoples in inland Australia and on
Australia's low-lying coastal islands are discussed in Moss (1994).

Adaptations to change in snowfields and glaciers are very limited. Artificial
snowmaking is a potential strategy for skifield operators, but only to a limited
extent because of the strong impact of temperature increases on snow amount,
the environmental impacts of the large water storage dams required, and the
costs involved.

Although many management and engineering adaptation options exist, the magnitude
of the financial exposure and the considerable time and expense involved in
adaptations indicate a high vulnerability with respect to hydrology.